Thank you for your question we asked Dr Sicherer to comment:
"Assuming the infant is truly allergic to cow’s milk in the form of cottage cheese and not to other forms of cow’s milk protein in foods (yogurt, milk based formula etc.), my first comment is that this is quite rare and perhaps unique. I have been unsuccessful thus far finding such a report.
Of course, I am working on the assumption that a full review of other potential trigger foods ingested at the time, and review for other non-food triggers, failed to identify another culprit. I would not rely on a positive skin test to cottage cheese to conclude that the cottage cheese was a potential trigger unless other explanations are exhausted.
I surveyed 10 of my experienced colleagues at the Jaffe Food Allergy Institute and we have not come across this exact situation. Of course, there is no reason to exclude the tolerated milk products from the diet, but this likely raised questions about other cheeses as well if they were not introduced yet. Certainly, there can be differences in allergenicity based on processing of milk proteins in production of various products, and certainly there could be differences in the relative concentration of different proteins in milk products, and there could be additives or processing agents to consider. Reactions in cow’s milk tolerant individuals to milk/cheese of other mammalian origin is described, and also reactions caused by other components in milk-based products (additives, enzymes). However, these do not seem to be likely explanations based on the material in your presentation.
Based on my own thoughts and suggestions from colleagues, the following additional considerations are provided.
1) Is this contact urticaria versus systemic milk allergy? The skin test with straight cottage cheese may be more “concentrated” or irritant-inducing than a milk extract or whole milk skin test and the hives may have been from direct skin exposure. I would query more about the sites of the hives (it is described as facial, but was it areas of direct contact with the cottage cheese) and if direct contact could be an explanation. If the infant has facial eczema that may also be a risk for having more contact-related hives from messy eating.
2) Review the specific brand of cottage cheese and compare with other brands regarding the ingredient list, with an eye towards identifying a non-cow’s milk protein ingredient trigger. In addition to the milk, and cream and enzymes that are common to most brands, many brands also have locust bean gum, carrageenan, guar gum, modified food starch, and live active cultures or natural and artificial flavoring. Cottage cheese is traditionally made without rennet, another rare potential allergen. Consider skin testing with different brands to address the chance that the causal brand has something unique to query the company about or that could be identified through a process of elimination or specific testing. Cross check ingredients in the cottage cheese against other foods the infant has eaten as well.
3) Has the infant ingested other cheeses? If not, there would presumably be concern to introduce them and additional skin tests and oral food challenge to other cheeses may be interesting to pursue.
4) Ultimately, it would seem that if multiple cow’s milk protein products are tolerated and no other ingredient is identified, a food challenge to cottage cheese may be warranted at some point later to confirm.
5) It may be interesting to see if serum IgE tests for cow’s milk, casein and the whey proteins are positive.
Scott Sicherer, MD, FAAAAI
I hope this is helpful.
Andrew Murphy, MD, FAAAAI